Conduction issues

Question 1

List the ECG criteria for a LBBB.

Answer 1

• QRS >0.12s
• V1-2: deep, broad S-wave (or w-shaped qS wave)
• V5-6, I and aVL: broad, “clumsy” completley positive R-wave
• Discordant ST elevation and depression

Question 2

List the ECG criteria for a RBBB.

Answer 2

• QRS >0.12
• V1-2: RsR’ pattern (R’ almost always larger
• V5-6, I and aVL: Broad S-wave
• Downsloping ST in V1-2 +/- inverted T-waves.
• T-waves positive in lateral leads

Question 3

List the ECG criterior for a LAFB.

Answer 3

• LAD
• Lateral leads: qR
• Inf’r leads: rS

Question 4

List the ECG criterior for a LPFB.

Answer 4

• RAD
• Lateral leads: rS
• Inferior leads qR

Question 5

What is bifascicular block?

Answer 5

Either:

• LAFB + RBBB or
• LPFB + RBBB

Question 6

What is tri-fascicular block?

Answer 6

1`HB + LAFB/LPFB + RBBB

Question 7

List the types of heart block.

Answer 7

• First degree - PR > 200ms - all PR comlexes -> QRS
• Second degree: some PR complexes -> QRS
  
  • Mobitz Type 1 - Wenkebach - ing’g duration of PR intervals
  • Mobitz Type 2 - constant PR intervals with dropped beats
• Third degree: no Pr complexes -> QRS - AV dissociation